Law-enforcement officers must communicate the Miranda rights to suspects who are in custody and subject to interrogation. But what, exactly, does it mean to interrogate someone?
A primary definition of "interrogate" according to Merriam-Webster is "to question formally and systematically." But interrogation in the context of Miranda is much broader: It includes express questioning about suspected criminal activity (for example, "Did you punch the victim?"), even if that questioning isn't formal or systematic. In addition to express questions, it includes words or actions that the police should have known were reasonably likely to elicit an incriminating response from the suspect.
For further discussion of what constitutes interrogation, including examples, see Do officers have to read the Miranda rights before talking to a suspect?